The disclosure of Japanese Patent Application No. 2001-076581 filed on Mar. 16, 2001 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
1. Field of Invention
The invention relates to an intake device of an internal combustion engine, and more particularly, to an intake device of an internal combustion engine for controlling an intake flow within an intake pipe by means of an intake flow control valve.
2. Description of Related Art
Conventionally, an intake device of an internal combustion engine is known to include an intake flow control valve between a throttle valve within an intake pipe and a fuel injector located downstream of the throttle valve. An example of such an intake device is disclosed in Japanese Patent Application Laid-Open HEI09-4474.
In this intake device, the intake flow control valve is closed from the time when the internal combustion engine is started (e.g., the starter motor is started until the engine speed exceeds a predetermined value), in order to close an intake passage more tightly. Such tight closing of the intake passage produces a large negative pressure within the intake passage downstream of the intake flow control valve. As a result, the fuel injected from a fuel injection valve is atomized so as to facilitate combustion. This intake flow control valve has a hole or notch. The air flow is supplied into a combustion chamber through the hole or notch, thereby forming a stronger tumble flow within the combustion chamber. This enables combustion with a reduced fuel amount, suppressing emission of unburned fuel.
Various shapes of the intake flow control valve have been proposed. The inventors found that, if there is a projection within the intake pipe located downstream of the intake flow control valve, the intake flow control valve shaped as proposed in the related art may not form a tumble flow within the combustion changer strong enough to effectively improve combustion of the engine. The inventor thus arrived at the invention in order to solve such a problem.
It is an object of the invention to provide an intake device of an internal combustion engine including an intake valve shaped so as to be capable of effectively forming a tumble flow within a combustion chamber even if there is a projection within an intake pipe located downstream of the intake valve.
In order to solve the above problem, an intake device of an internal combustion engine according to one aspect of the invention includes: a throttle valve provided within an intake pipe; a projection within the intake pipe located downstream of the throttle valve; and an intake valve provided between the throttle valve and the projection, for producing a tumble flow in a combustion chamber, in which the intake valve is shaped so that an airflow formed by the intake valve bypasses the projection located downstream of the intake valve.
The intake valve having such a shape allows an airflow formed by the intake valve to bypass the projection within the intake pipe located downstream of the intake valve. Therefore, the airflow is introduced into the combustion chamber without being weaken nor disturbed. This enables formation of an effective tumble flow within the combustion chamber, allowing improved combustion of the internal combustion engine.